Fix coin count and value statistics

[braydonf]

Closes #959

[pinheadmz]

Importing the discussion from the issue:

Okay so #960 should resolve the issue for new synchronizations.

To fix existing synchronizations there could be:

A manual script that adjusts the values to decrease the txouts by 2 and total amount by 100. The script would need to be run only once and if necessary.
A database version upgrade and a migration script that will decrease the txouts by 2 and total amount by 100. This provides more automation.
A database version upgrade with paired with other database updates. Minimizes database upgrades.
Fixing existing versions are eventually handled by re-syncing. Considering it's a small fix, this is not very efficient.

We could copy the approach in this PR to Handshake for a similar issue:
https://github.com/handshake-org/hsd/pull/396/files
(add a migration ID to the DB and run it once automatically on boot)

[codecov-io]

Codecov Report

Merging #960 into master will increase coverage by 0.01%.
The diff coverage is 91.48%.

@@            Coverage Diff             @@
##           master     #960      +/-   ##
==========================================
+ Coverage   62.10%   62.12%   +0.01%     
==========================================
  Files         156      158       +2     
  Lines       26077    26095      +18     
==========================================
+ Hits        16195    16211      +16     
- Misses       9882     9884       +2     

Impacted Files	Coverage Δ
lib/node/rpc.js	30.20% <ø> (ø)
lib/blockchain/internal/cache.js	86.84% <86.84%> (ø)
lib/blockchain/chaindb.js	74.29% <87.50%> (-2.64%)	⬇️
lib/blockchain/internal/records.js	94.25% <94.25%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6beb54d...7afc3c7. Read the comment docs.

[braydonf]

Regarding migration, the existing db version and migration scripts could benefit from increased automation. There is an argument to not want the database to automatically upgrade, especially if it will take some time. So it may be useful to have a flag that can be sent at startup to perform automatic database upgrades, and would default to false. So instead of running the migration script manually, it could be to include a --migrate flag at startup or similar cli tool.

[pinheadmz]

Update looks good, utACK for now @ 0a82ad9

[braydonf]

Okay, I've started the migration script (untested) by adding it to the existing migration scripts. It should update the database version and fixes bip30 duplicate issues for existing databases. It was necessary to expose ChainState and ChainFlags for usage in the migration.

[braydonf]

Also realized that, technically disconnectBlock will need to also have corresponding changes.

[braydonf]

I've run a sync with the changes and it confirms it, and have the correct txouts count.

[braydonf]

I've added corresponding code for disconnectBlock, it also applies to removing the coins, because the coins should still exist (for the duplicate).